Effects of external factors on red blood cell concentrate quality during helicopter transport: a pilot study

Prehospital red blood cell concentrate (RBC) transfusion is clinically advantageous and has an impact on all-cause mortality, especially in cases of major traumatic hemorrhage. The most frequent mean of prehospital transportation for blood and blood products is the helicopter. However, data on how external conditions during the helicopter flight affect the RBC quality are currently insufficient. There are also no data on how long the latter can be transported by helicopter without qualitative changes. This study aims to investigate how helicopter flight conditions affect RBC quality and to determine the maximum safe transport duration.

Four pairs of RBCs from different donors were taken. Each RBC pair was first mixed and homogenised, and then divided into two parts. The first was transported by helicopter for 22 successive days and the second served as control and was stored at 2 °C-6 °C. On days 1, 8, 15, and 22, samples of each RBC were taken, and hemolysis rates were calculated. A final sample was taken on day 36, which also marked the expiry date of the RBCs.

The study maintained stable storage temperatures within the ideal range throughout helicopter transport. Despite variable conditions including number of starts/landings, flight time, outside temperatures, wind speed, and the cabin temperature, the hemolysis rates of transported RBCs did not differ significantly from those of control RBCs (median 0.061% vs. 0.066%, P>0.4). Furthermore, after 14 days of post-transport storage (day 36), hemolysis rates in both groups remained well within acceptable limits (0.151% vs. 0.133%).

External conditions during helicopter transport for 22 d do not affect the RBC quality in terms of hemoglobin, hematocrit, free hemoglobin and hemolysis rate, rendering RBC transport and administration safe.